1. Field of the Invention
This application relates to tools especially adapted for changing brake shoes on an automobile, truck, or other vehicle that has a brake drum.
2. Description of Related Art
U.S. Pat. No. 5,058,414 issued to patentee Hayes, the disclosure of which is fully incorporated by reference herein, shows an electrical knock-out method and tool. Like the invention herein, the tool shown by Hayes uses a pliers like action. Hayes shows method of removing electrical box knock-outs which includes utilizing a hand tool which has elongated jaws, one with a ring and the other with a punch directed toward the center of the ring. By positioning the jaws on opposite sides of a box wall and closing the jaws, the punch and ring close on the knock-out and the punch deflects the knock-out through the ring so that the knock-out can then be twisted and removed by needle nose pliers.
The ring is preferably larger than the knock-out and the punch is smaller than the internal diameter of the ring and preferably about half that size. The tip of the punch may be designed to deflect the knock-out away from the wall on the side corresponding to the open face of the box. The punch may be lined up with a selected concentric ring edge to deflect and remove the ring. The tool may also be used to straighten inadvertently deflected rings or knock-outs. The tool is convenient to carry, may be operated with a single hand and saves significant time and aggravation in the wiring process. The tool of Hayes is not designed to operate on brake drums, nor does it have the advantageous vice-grip action of the instant invention.
U.S. Pat. No. 6,000,686 issued to patentee Yates shows a three-way clamp that locks closed using the action associated with a common vice-grip, the disclosure of which is fully incorporated by reference herein. In accordance with the various features of the Yates invention, a locking, three-way clamp is provided. The locking three-way clamp includes a handle, threaded adjusting screw and toggle lock typical of state of the art locking c-clamps or locking pliers. Opposing jaws that are in spaced relation are also provided. A workpiece restraint member is provided at the conjunction of the jaws and proximate the central pivot point around which the jaws pivot. The locking three-way clamp of the Yates invention also includes an engagement device disposed on the distal end of each jaw. Each engagement device includes a workhead that defines a point of contact between the clamp and a workpiece. Upon closure of the jaws such that the workhead engages the workpiece, the engagement device pivots inward towards the restraint member thus applying a vector force having a component vector towards the workpiece and a component vector towards the restraint member. Rather than overcoming the frictional force between the opposing workheads and the workpiece and forcing the three-way clamp off of the workpiece, as is problematic with state of the art three-way clamps, the resultant vector force forces the workpiece against the restraint member and forces the clamp towards the workpiece.
In one embodiment of the locking three-way clamp of Yates, the engagement device is defined by a pair of opposing, eccentrically mounted cams. In this regard, opposing cams are pivotally connected at the distal end of each jaw. The cams each rotate around the cam's eccentrically positioned pivot point. The cams are, preferably, spring-biased away from the closed position. Moreover, the cam is mounted such that the radius between the central pivot point of the clamp and the eccentrically positioned cam pivot is greater than the radius between the central pivot point of the clamp and the point of contact of the cam with the workpiece and further such that the point of contact of the cam with the workpiece is disposed inside a line between cam pivot points. This configuration allows the cams to rotate towards the restraint member when the jaws are closed and the cams engage the workpiece. As a result of this rotation, a bidirectional vector force which has essentially x- and y-component vectors is applied against the workpieces. This results in the workpieces being biased towards the restraint member.
In another embodiment of the locking three-way clamp of Yates, the engagement device is defined by a linkage assembly pivotally secured proximate the distal end of each jaw of the clamp, each linkage assembly including a pivotally mounted workhead. In this regard, the linkage assembly has first end pivotally secured proximate the distal end of the jaw. The linkage assembly is spring biased towards the open position. Further, the distal end of the jaw is inclined so as to permit flexion of the linkage assembly towards the restraint member. The second end of the linkage assembly is pivotally secured to the workhead. The workhead includes a pad for providing a point of contact with the workpiece. In the preferred embodiment, the pad is substantially planar. The first and second pivot points are in spaced relation to each other and are configured such that the radius between the central pivot point of the clamp and the first pivot point is greater than the radius between the central pivot point of the clamp and the second pivot point and further such that the second pivot points are disposed inside a line between the first pivot points when the pad engages the workpiece. This configuration results in application of a bidirectional vector force which has x- and y-component vectors upon closure of the jaws and engagement of the workheads against the workpiece.
United States published patent application No. 0005798 A1, filed by Kuchar, the entire disclosure of which is expressly incorporated herein by reference, shows a stud installation tool for installing a traction stud onto a resilient endless belt. The studs have a threaded shank with a terrain engaging end and an opposite end mounting an enlarged head which is adapted, when installed, to bear against an inner face of the endless belt. The threaded shank when installed is adapted to threadedly receive a threaded nut on the outer face of the endless belt. The stud installation tool comprises a pair of swingably coupled clamping heads moveable between spaced apart open positions and closed positions detachably clamped to the opposite sides of the belt. One of the clamping heads is detachably mounted to the enlarged head of the traction stud; the other of the clamping heads has an aperture therethrough for freely receiving the terrain engaging end when the clamping heads are in the closed position. Handles are provided for swingably moving the heads between the open and closed positions to push the terrain engaging end through the belt from the inside face to the outer face and clamp the stud while a tool fastens a fastener to the threaded shank.